Help! F355 ABS Gremlins (one for the electrical gurus)

Sorry, no idea. USA, Canada and Aus cars were not fitted with the unit, just a jumper wire (or plug?). Galactica, if you could tell us where you're from, we might be able to discount this as a possible cause

 

Looking at that diagnosis, the diode may have been incidental. The technicians sound reasonably competent*, so it's not likely they were listening for pump operation if the accumulator already had sufficient pressure.

I wouldn't worry about an ECU just yet. The fault chart suggest a problem with the left front delivery valve (which might be an ECU problem)

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If it is an ECU power transitor problem, Miro is probably the best person to help you with finding a new or substitute transistor. You just have to figure out which transistor drives the left front delivery valve. It should be attached to pin 35 on the ECU. The pin has a black-violet wire on the car side (although if the plug on Teves unit is the same as the one on the Bosch system, you may not be able to see the wire colours unless you dismantle the plug shell).

If a replacement ECU is required, some have replaced them with cheaper ECUs from other (non-Ferrari) vehicles, but whether you want to risk that, I don't know.

*apart from saying a shorted diode was responsible for the loss of power.

 

Sorry.. going cross-eyed here... It's a blue wire.

 

Here is my hint to you. Bring a copy of Ian's color wiring diagram in to the shop and ask him to CONFIRM all wiring to the four ABS system relays are correct. He will be a little offended by a customer telling him what to do but … this is the second time in for the same problem. He needs help.

Ask him to point to the diode on the diagram, the diode that he replaced by soldering it in the last time. Ask for an explanation of what that diode did to cut power to the relay. You spent $2000, you can use an explanation for it to happen again.

 

Just to confirm... You have a 2.7 car with a stick shift? There are slight variations from car to car, requiring different wiring diagrams.

I had forgotten you have both ABS and brake lights on. The brake warning light comes on for low fluid pressure and low fluid quantity (and brake wear, but this is obviously not the issue). This kind of isolates the problem to fluid pressure (or fluid pressure control) or to fluid quantity. In a sense, these lights are independent of each other, but if you get an issue with pressure or fluid, obviously this is going to generate both lights.

If you had, say, a pressure sensing switch problem (indicating high pressure all the time), the ECU might not turn on the pump. With no pressure in the system, this will generate the brake warning light and the ABS fault light. Would this generate that 2.2 code though? It would help if you knew which parameters the ECU is using to isolate the various faults (and generate the codes). With a pump not working, you might think that the ECU would generate a "6.1" code (low pressure or fluid level), but it didn't. What other parameter/s is the ECU monitoring other than pressure to isolate these problems? And does the ECU put a time stamp on these codes? How do we know that 2.2 code was just a one time glitch that never came back?

 

Since you don't have the "Electronics for ABS system cut-off", the only things that can cause no running of the pump are either bad pump, bad pump relay, bad pressure switch or bad wiring between the relay, the pressure switch and the pump motor. The pump is not operated by the ECU, only by the pressure switch and the key in ACC. Even if there are other faults in the ABS system, the pump should come "on" the moment you turn the key to ACC (if the pressure in the brake accumulator has been discharged; this is achieved by pumping the brake pedal some 20 times with the key off).

The relay for the pump is black and it may look like a standard relay but it is not. It has two diodes inside it (more diodes!), as can be seen on the wiring diagram. There should also be a diagram on one side of the relay also showing these diodes. A simple test would be to take the relay out and jump the socket pins 30 and 87 (see the pinout below), with the ignition key off/out, and see whether the pump runs. If it does, either the relay or the pressure switch is bad (assuming that all pins in the relay socket are good/clean) or there is a problem in the wiring pressure switch to the relay.
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By the way, it is good that your mechanic cleaned out all the dielectric grease. I don't think it was factory but probably applied by the PO. This grease should not be applied to pins and/or sockets as it is non-conductive, i.e. it's an isolator (the mechanic incorrectly stated that the grease "lost conductivity"). The dielectric grease is designed to be used only in sealed connectors and only a small amount on the sealing surfaces/gaskets, to improve sealing, but some people put it all over the place. If it was conductive, multi-pin connectors would be shorted if the grease was applied directly on all its pins and sockets.

 

The ones who don't like to waste money, do

I see the power for the pump relay solenoid goes to pin 87a of the Auxilliary ABS relay. Might faulty contacts or pins on this relay also cause a problem? Pin 87a seems to get power from the 3amp fuse (through the relay contacts), but I don't understand how that line going to the cutout (or jumper) affects the circuit. What happens at pin 2 of the ECU?

I'd be tempted to change a few relays and clean up the relay sockets before taking the car to a service centre, especially when you have an intermittent defect.

 

Very good point. If the Auxilliary ABS relay is faulty (the NC 87a is corroded or contaminated), or if the 3A fuse is blown, the pump relay will not get ACC switched +12V on one side of its solenoid so it will not engage when commanded by the pressure switch. Definitely the first thing to check, Auxilliary ABS relay and the 3A fuse. I have experienced one or two cases of the 87a NC contacts on relays being non-conductive due to some oxidation. The ABS Aux relay 87a contacts conduct rather small current (not much self-cleaning) and, as they are not pressed together hard (bing NC), it is quite possible that they have lost connectivity.

 

The Auxilliary (orange/yellow) relay seems to have Ferrari part number 131940 and is sometimes called a system release relay.

The black pump relay seems to have part number 158090. Both are quite expensive for Aussies. Are these likely to have Hella or Bosch substitutes?

I wonder if Jaguar Teves relays are compatible:

https://www.terrysjag.com/product/DAC4506.html

 

I get the clunks as well so it appears to be normal. I don't seem to hear them every time though but quite often. I have not investigated but it could be coming from some emission solenoid or PCV solenoid valve?

 

The relay cover seems to be plastic, so it shouldn't be too hard to get inside to clean the contacts. Might save a few hundred Aussie dollars on new relays and might get the car back on the road again quickly. Of course, you have to access the relays (luggage liner/s to remove).

 

I have a relay (white) from one of my ex-BMWs (E30 I think, Siemens V23134-C52-X90 and another number 12.63-1729004 which could be the BMW p/n) which also has two diodes, orientated like the Ferrari's pump relay. I think it is the main engine ECU relay on the BMW. I have not seen any relays from other cars that are same as the Ferrari's Aux relay. If I needed to replace any of these "special" relays, I would just use a normal 30-87 or 30-87/87a relay which already has an internal diode across pins 85-86 (easy to find and the diode is always orientated in the same way, cathode to 86) and solder an external in-line diode. This is what Jaguar actually did in their, similar to the Ferrari's, Teves ABS system (I think I posted this Jag diagram in an ABS thread some time ago).

 

I found more info on the BMW relay that can be used as the Ferrari ABS pump relay:

BMW Nos. 12 63 1 729 004, 12631729005, 12631711266
Siemens V23134-C52-X90
Tyco V23134-C52-X90
Bosch 0 332 019 109

BMW 3' E30 1982 - 1994
BMW 3' E36 1989 - 2000
BMW 5' E28 1980 - 1987
BMW 5' E34 1987 - 1996
BMW 5' E39 1995 - 2003
BMW 7' E32 1985 - 1994
BMW 7' E38 1993 - 2001
BMW 8' E31 1989 - 1996
BMW Z1 Roadster 1988 - 1991
BMW Z3 E36 1996 – 2000

It appears fairly easily available, examples: Bosch, USD 13 at https://www.amazon.com/Bosch-0332019109-Relay/dp/B004AG0MVM, Siemens at €15 at https://www.tav-autoverwertung.de/shop/Relay-BMW-12631729004-Siemens-V23134C52X90

 

Ian, I had a look at the Jag, 348 and 355 Teves ABS diagrams. Connections to the ECU pins of the Wheel Sensors (Pins 22, 23, 24, & 25) and the Solenoid Valves are identical between Jag and 348. I verified this by looking at the 348 diagram and page G38 of the Service Manual.

The 355 has the same ECU pin connections to the Solenoid Valves as the 348 (compare 348 page G38 with 355 page G34) therefore connections of the 355 Wheel Sensors should be the same as in the case of 348 (Pin 22 Right Rear, Pin 23 Left Front, Pin 24 Left Rear, Pin 25 Right Front). However, there appears to be an error in the 355 ABS diagram (page L36) which shows at the top left corner "Left Front" (correct), at the top right corner "Left Rear" (should be Right Front), at the bottom left corner "Right Front" (should be Left Rear) and at the bottom right corner "Right Rear" (correct).

Here's the 1989 Jaguar XJS diagram for your reference. I have written the ECU pin numbers at the wheel sensors and solenoid valves (same as 348). You will note that the ABS pump relay has both diodes installed externally, in the same orientations as the Ferrari pump relay internal diodes, and the Jag relay is just a standard NO relay.
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As pointed by Ian and as I suggested in Post #40, check first the Auxiliary (orange or yellow) relay - it should have continuity between its Pins 30 & 87a when the relay is off. Also check the 3 Amp fuse. If this relay is faulty, it will light-up both, the ABS and the Brake, warning lights. It may be the only thing causing problem with your ABS.

The Auxiliary Relay is not used in the case of Jag ABS and on 348/355 it is there just to disable the ABS Pump during cranking (probably just to reduce load on the battery). I know that it lights-up the ABS warning light from experience with my 348. When I bought it, it had a problem engaging the starter motor due to a bad contact (in the 9-pin connector in engine compartment) in the wire going to the starter solenoid so, before I discovered the fault, I would have to turn the key to START many times (with nothing happening with the starter motor) and, after 4-5 attempts, the ABS light would come on even though there was nothing wrong with my ABS. I now understand that every time I turned the key on-off to the START position, the Auxiliary Relay was switched on-off (or off-on for the supply to the pump relay solenoid). Seems that this repeated switching of the Auxiliary Relay many times in succession (and the engine not starting) was understood by the ABS ECU as fault of the relay and it lit-up the ABS warning light. When I eventually started the engine, the ABS light would go off.

 

Well-spotted. Makes sense... even the position of the sensors on the diagram seems wrong. The 348 diagrams have highlighted quite a few errors in the 355 diagrams over the years.

New diagrams uploaded...

F355 (2.7) Fig4_Teves_ABS_System

F355 (5.2) Fig4_Teves_ABS_System

F355 (2.7) Wiring Diagrams (zip file)

F355 (5.2) WiringDiagrams (zip file)

Thanks, Miro.

 

Sometimes measuring voltage can be misleading. The positive feed to the pump motor (to the dangling dongle on the diagram) is also connected to the ABS ECU (Pin 32) so the 12.3 V might be coming from the ECU and not from the pump relay. Just to be certain, connect a bulb to the pump feed connector pins and, if it lights-up when you turn to ACC, the relay is good and the pump motor is bad.

If you verify that there is supply to the motor "dongle" and the motor is not running, the motor, or the pump, should not be a seized as it would have blown the 30A fuse (is it still good?). It is more likely that the motor brushes and/or the commutator have corroded and lost contact. Sometimes, knocking on the motor (with a plastic hammer) while the power is on can get it running.

If you have to replace the motor, you can get a Jaguar used one rather cheaply. It is easy to detach the motor from the pump (two screws) and do a swap. There is a lot of writing on the forum (do a search) about using a motor from a Jaguar pump or using the whole Jaguar pump/motor assembly with a conversion kit available from one of the members here.